Firing device, method, and system, for seismic exploration

ABSTRACT

The invention provides: 1. A FIRING DEVICE FOR UNDERWATER SEISMIC SHOOTING SMALL DELAYTYPE PERCUSSION-INITIATABLE CHARGE ASSEMBLIES INCLUDING (A) MEANS FOR SEQUENTIALLY CONVEYING SUCH CHARGE ASSEMBLIES INTO, OR ALONG, A PATH OF FORWARD TRAVEL FOR PERCUSSION INITIATION, (B) MEANS IN SAID PATH OF TRAVEL FOR INTERCEPTION-CONTACT, WHILE IN A STATIONARY POSITION, WITH THE FORWARDLY MOVING CHARGE ASSEMBLIES TO CAUSE PERCUSSION INITIATION OF SAME BY RESULTING IMPACT, AND (C) MEANS FOR DIRECTING THE THUSINITIATED CHARGE ASSEMBLIES, DURING THE DELAY PERIOD, FROM THE SYSTEM FOR SUBSEQUENT DETONATION; 2. AN UNDERWATER SEISMIC EXPLORATION METHOD INCLUDING THE STEPS OF (A) SEQUENTIALLY CONVEYING SUCH DELAY-TYPE CHARGE ASSEMBLIES INTO OR ALONG THE ABOVE SAID PATH OF TRAVEL, (B) SEQUENTIALLY IMPACTING SAID ASSEMBLIES DURING THEIR TRAVEL TO PROVIDE THE PERCUSSION INITIATION, AND (C) DURING THE DELAY PERIOD, SEQUENTIALLY DIRECTING TRAVEL OF THE THUS-INITIATED CHARGE ASSEMBLIES AWAY FROM THE ZONE OF PERCUSSION INITIATION INTO AN ADJACENT UNDERWATER AREA FOR DETONATION; AND 3. A SYSTEM FOR GENERATING SEISMIC DISTURBANCES IN AN UNDERWATER ZONE INCLUDING (A) A MOVABLE PLATFORM, SUCH AS A BOAT DECK, (B) A FIRING DEVICE, ABOVE DESCRIBED, AS A SUBMERSED FIRING STATION, AND (C) MEANS FOR DELIVERING SUCH CHARGE ASSEMBLIES UNDER FORCE OF FLUID PRESSURE FROM THE BOAT DECK TO THE FIRING STATION, INCLUDING A DELIVERY CONDUIT AND PRESSURE GENERATION MEANS THEREFOR.

United States Patent ABSTRACT: The invention provides:

1. a firing device for underwater seismic shooting small delay-type percussion-initiatable charge assemblies including (a) means for sequentially conveying such charge assemblies into, or along, a path of forward travel for percussion initiation, (b) means in said path of travel for interception-contact, while in a stationary position, with the forwardly moving charge assemblies to cause percussion initiation of same by resulting impact, and (c) means for directing the thus-initiated charge assemblies. during the delay period, from the system for subsequent detona- 2. an underwater seismic exploration method including the steps of (a) sequentially conveying such delay-type charge assemblies into or along the above said path of travel, (1)) sequentially impacting said assemblies during their travel to provide the percussion initiation, and (0) during the delay period, sequentially directing travel of the thus-initiated charge assemblies away from the zone of percussion initiation into an adjacent underwater area a system for generating seismic disturbances in an underwater zone including (a) a movable platform, such as a boat deck, (b) a firing device, above described, as a submersed firing station, and (c) means for delivering such charge assemblies under force of fluid pressure from the boat deck to the firing station, including a delivery conduit and pressure generation means therefor.

[72] inventor Richard R. Larson Ulster Park, N.Y. [21] Appl. No. 818,475 [22] Filed Apr. 21, 1969 [45] Patented Apr. 13, 1971 [73] Assignee Hercules, Incorporated Wilmington, Del.

[54] FIRING DEVICE, METHOD, AND SYSTEM, FOR lion;

SEISMIC EXPLORATION 29 Claims, 19 Drawing Figs. 7 n [51 "us. Cl 102/22, 102/73,181/.5 [51] Int. Cl F42d 3/06 [50] Field ofSearch 181/.5 (XC); 102/22-24, 73, 75, 20,21

for detonation; and [56] References Cited 3 UNITED STATES PATENTS 3,216,320 11/1965 Thomas et a]. l02/22X 3,360,070 12/1967 Cholet et a1. l8l/.5(XC) Primary Examiner-Verlin R. Pendegrass Attorneywilliam F. Smith f5 8 ll 9\ t 1 I I I IIIII:

I L: z: :r'rL

L h m\ PATENTEU APR 1 3 |97l SHEEY 1 BF 3 Ila Ila

' FIG. IB

FIG. IC

54 CHARGE STORAGE WATER PUMP SYSTEM FIRING DEVICE (SEE FIGJ) COMPLETE CHARGE (SEE FIGZ) RICHARD R. LARSON INVENTOR BY SW C E ATTORNEY PATENTE!) APR 1 3 ml SHEU 2 0F 3 FIG. 28

FIG. 2A

FIG. 20

FIG. 2C

FIG.2

RICHARD R. LARSON INVENTOR SM/0111M ATTORNEY FIRING DEVICE, METHOD, AND SYSTEM, FOR SEISMIC EXPLORATION This invention relates to underwater firing of explosive charges to generate seismic disturbances. In one aspect this invention relates to a firing device for sequentially initiating percussion-initiatable explosive charges in a body of water and then directing the initiated charges outside the system for detonation in a seismic exploration zone. In another aspect this invention relates to a system, including the above firing device, for generating seismic disturbances in a body of water. In still another aspect this invention relates to a marine seismic exploration method utilizing a system above described. Other aspects of the invention will be apparent in light of the accompanying disclosure and the appended claims.

Seismic exploration involves the introduction of energy into the earth to initiate wave action for determination of characteristics of subsurface structures, and is based on the generation of seismic disturbances, or waves, in the earth's surface which are reflected or refracted from buried strata interfaces and the like.

It has been general practice, in the past, to detonate high explosives as the energy source for seismic exploration inasmuch as the energy generated provides for excellent seismic records. Unfortunately in offshore exploration, shock energy from detonation of high explosives, particularly in large amounts, is unduly damaging to certain marine life including many of the important food and game species. Transport of high explosive seismic charges to the offshore seismic shooting site is subject to the limited quantity that governing authorities permit on the loading dock at any one time to minimize the safety hazards involved, which, in turn, limits the amount of high explosives that can be handled on the dock and impairs the efficiency at which the explosives can be loaded across the dock and transported to the exploration site. Particularly for these reasons the industry, in offshore practice, has turned to the use of nitrocarbonitrate NCN'type seismic charges.

In offshore seismic exploration practice, the complete seismic charges are assembled on deck of a boat moving through the test area and then emplaced from the boat and detonated. General offshore technique in the handling of NCN charges on board ship has involved inserting a primer into the charge, inserting an electrically actuated detonator into the primer, attaching a depth control (float and string) to the assembled charge, and placing the charge in the water. Concurrently the boat travels at about 6 knots for a period sufficient to place a predetermined length of firing cable (position locater). Each such cycle requires a minimum of about 2 minutes, and accordingly, requires large charges, generally of from 50 to lOO pounds, in order that a sufiiciently strong signal be emitted at each test point.

The use of such large NCN charges is disadvantageous in many respects, viz. (l) explosive force from each detonation imparts damage to the hydrophone cable unless the cable is carried at a great distance from the detonation, and accordingly, general practice has been to utilize an additional boat for die cable thus incurring marked increase in costs; (2) a large quantity of these charges is necessarily maintained aboard ship which, in addition to the safety hazards involved, is economically undesirable from the standpoint of space, already at a premium, that must be available for storage; (3) such charges are of size and weight that they are difficult to handle aboard ship and particularly in heavy seas; and they require extensive manpower for loading at the dock and for being handled aboard ship for assembly and emplacement; (4) use of large NCN charges, in some instances, results in unduly high fish kill; and (5).communication lines from the boat deck to the charge. and auxiliary equipment, are always susceptible to becoming entangled to impair success of the shot, sometimes resulting in loss of the charge.

Small nitrocarbonitrate charges have been used in offshore seismic practice in an effort to overcome the disadvantages inherent in the use of larger charges. Such use of small nitrocarbonitrate charges has required emplacement and detonation of a proportionately larger number of charges in a given test area which in turn has required emplacement and shooting of charges more rapidly than were necessary in accordance with earlier practice. However even more so than for larger charges, the use of smaller charges has been seriously impaired by the unwieldy handling of the various communication lines from the boat to the charge and accordingly no appreciable advance has been provided by use of the smaller charges.

Numerous attempts, involving use of underwater mechanical devices, have been made to more rapidly assembly and position the charges to thereby reduce charge size and overcome the above disadvantages. However, such practice has been limited due to damage imparted to the mechanism by 'force of the resulting detonation except in those instances where the quantity of the charge has been limited to about one-tenth pound or less at which level the energy of the seismic signal is substandard.

This invention is concerned with a firing device for rapidly and sequentially initiating small seismic charges in an underwater zone and for then directing the initiated charges to an external point for detonation to provide a strong seismic record and for doing so without damage that might otherwise be imparted to the firing device by force of the detonation, and at a rate providing energy necessary for compensation of that normally delivered by larger, but less frequently fired, charges. The invention is further concerned with a seismic exploration system containing, and a seismic exploration method utilizing, such firing device.

In accordance with the invention an underwater firing device for initiating delayed percussion-initiatable seismic charge assemblies and then delivering the initiated charge for detonation outside the firing system, is provided, which comprises means for sequentially conveying said charge assemblies into, or along, a path of continuous forward travel for percussion initiation of same; means in combination with said conveying means at a forward point on said path of travel for sequential contact, while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same by force of resulting impact; and means for sequentially directing the thus-initiated charge assemblies away from said firing device during said period. Generally, the firing device includes open means for guiding the charge assemblies along the path of continuous forward travel; means for conveying the charge assemblies sequentially to the open guiding means and then into the path of continuous forward travel; and the means for contact is supported at a forward point on the guiding means.

The now-preferred firing device of the invention comprises a conduit, and a tray member extending from one end thereof; said tray member being adapted to sequentially guide such charge assemblies along a path of continuous forward travel thereon for percussion initiation of same, and for pivotal travel of the thus-initiated charge as described hereinafter, said conduit being adapted to sequentially convey such charge assemblies to said tray and into said path of forward travel; impact means secured to said device and disposed in said path of forward travel for sequential contact with each said charge assembly to cause percussion initiation of same by force of resulting impact; said impact means being spaced as, and forming, a pivot for directing pivotal travel of said charge assembly from said tray member after said impact.

Any suitable percussion-initiatable charge assembly can be fired in the firing device of the invention, now preferred of such charge assemblies are those disclosed in the copending application of Pitch and Hamilton Ser. No. 673,594 filed Oct. 9, I967, and now US. Pat. No. 3,509,820 and Fitch, Guenter and Schlutter Ser. No. 724,942 filed Apr. 29, I968. Those assemblies. as applied in practice of the present invention, are elongated and each comprises a small NCN-type seismic main explosive charge in combination with a percussion-initiatable primer element, the percussion-sensitive portion being positioned in one end of the charge assembly and being generally an empty primed rifle cartridge case, more often of the rim-fired type.

Further in accordance with the invention, a system for generating seismic disturbances in a body of water is provided, which comprises a movable platform; means on said platform for storage of percussion-initiatable seismic explosive charge assemblies; a firing device, as a submersed firing station, comprising (1) means for sequentially conveying said charge assemblies along a path of continuous forward travel for percussion initiation of same, (2) means in combination with said conveying means at a forward point on said path of travel for sequential contact, while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same by force of resulting impact, and (3) means for sequentially directing the thus-initiated charge assemblies away from said conveying means during the period of said delay; a delivery conduit connecting said platform with said conveying means of said submersed firing station; fluidpressure-generating means on said platform connecting with said delivery conduit for sequentially moving said charge assemblies from said platform through said delivery conduit to said conveying means, and then into and along said forward path of travel for said initiation.

The submersed firing station in the system of the invention is generally the now-preferred firing device, often of integral construction, as described more fully herebelow. Although the system can utilize any suitable movable platform, the latter is generally the deck of a boat for towing the firing station through the marine seismic zone.

Although any suitable means can be utilized in combination with the above-described system, for detecting water pressure variations caused by the seismic disturbances, a streamer cable coupled to a towboat as the movable platform, in combination with conventional auxiliary means on the boat deck, is generally utilized.

Further in accordance with the invention a seismic exploration method is provided wherein a complete delayed percussion-initiatable seismic charge assembly is emplaced and fired in an underwater zone to provide energy for a seismic record, said method comprising sequentially conveying a plurality of said charge assemblies into, and along, a path of forward travel in said underwater zone; sequentially impacting said assemblies concurrently with travel of said assemblies along said path to percussion initiate same; and during the period of said delay, sequentially directing travel of the thus-initiated charge assemblies away from the zone of said percussion initiation into an adjacent area in said underwater zone for detonation.

The seismic exploration method is carried out utilizing a firing device of the invention in accordance with the steps comprising sequentially delivering a plurality of the charge assemblies under force of fluid pressure into a chargeconveying means of the firing device in an underwater zone; the firing device comprising (1) means, as said chargeconveying means, for sequentially conveying said charge assemblies along a path of continuous forward travel for percussion initiation of same, (2) means in combination with said conveying means at a forward point on said path of travel for sequential contact, while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same by force of resulting impact, and (3) means for sequentially directing the thus-initiated charge assemblies from said firing device during the period of said delay; regulating said fluid pressure so as to impart sufficient force of impact for said percussion initiation with concomitant initiation of said charge assemblies and subsequent delay of priming action thereof, whereby during the period of said delay, travel of the thus-initiated charge assemblies is sequentially directed away from the zone of said percussion initiation into an adjacent area in said underwater zone for detonation. Generally, the firing device utilized includes open means for guiding the charge assemblies along the path of continuous forward travel; means for conveying the charge assemblies sequentially to the open guiding means and then into the path of continuous forward travel; and the means for contact is supported at a forward point on the guiding means. More often the method of the invention utilizes the nowpreferred firing device above described.

Although the seismic charge assembly can be delivered to the firing device from any suitable point, the method of the invention, in preferred practice, utilizes a towboat for moving the firing device through the exploration area, with extension of a delivery hose from the boat deck to the assemblyconveying means of the firing device. The percussioninitiatable charge is generally that above described with reference to copending applications, Ser. Nos. 673,594 and 724,942....

The invention is illustrated with which:

FIG. I is a cross-sectional view of a now-preferred embodiment of firing device including a conduit-tray assembly of integral construction together with percussion contact means which also serves as a pivot for pivotal travel of the initiated charge for detonation outside the system, and FIG. IA is an end view thereof;

FIGS. 18 and 1C are, respectively, cross-sectional views of tapered conduit inner wall structure and nonintegral conduittray construction, embodiments of a firing device of the invention;

FIG. 2 is a cross-sectional view of a now-preferred form of percussion-initiatable delayed seismic charge assembly fired in a firing device of the invention; therein;

FIGS. 2A and 2B are enlarged partial views in cross section of optional embodiments of the primer element of the assembly of FIG. 2, illustrating two types of delay fuse structure that can be utilized therein:

FIGS. 2C and 2D are each enlarged cross-sectional views of separate embodiments of suitable percussion-initiator means for the assembly of FIG. 2;

FIG. 3 is a view in perspective of the firing device of FIG. 1, and is further illustrative of the operation thereof with reference to dotted lines illustrating the position of a complete assembly of FIG. 2 when emplaced therein for percussion initiation;

FIG. 4 is a diagrammatic illustration of seismic exploration system. and method, utilizing a firing device of the invention;

FIG. 5 is a cross-sectional view of an embodiment of firing device including structure for lateral travel of the initiated charge for the subsequent detonation, and FIG. 5A is an end view thereof;

FIG. 6 is a cross-sectional view of an embodiment of firing device utilizing a conduit as the sole means for conveying charge assemblies for the percussion initiation, and FIGS. 6A and 6B are auxiliary views thereof; and

FIG. 7 is a cross-sectional view of an embodiment of firing device containing pivotally supported structure serving as contact means for the percussion initiation and also as means for directing the initiated charge from the firing system for detonation, and FIGS. 7A and 7B are, respectively, end, and auxiliary, views thereof.

Referring to FIG. 1, percussion-initiated explosive charge assembly conveyor conduit 11 of firing device 9 is threaded (threads 7) at rearward end 8 for connection with a suitable hose-type delivery conduit 6 for sequentially receiving elongated delayed percussion-initiatable seismic charge assemblies 5 from hose 6 and then conveying them through forward end 13 for percussion initiation.

Open guide-support means 10 is a suitable tray-type member adjacent and immediately forward of conduit II, and is in open communication and direct alignment with conduit II for sequentially receiving the delay-type percussioninitlutttblc seismic charge assemblies from conduit 11, as they are moved axially from conduit II; and for guiding each charge assembly along a path of continuous forward travel to wheel-type contact, or firing pin, means 12 at or near the forreference to the drawings of ward end b of guide member 10. Guide member 10 is open for subsequent pivotal travel of the seismic charge assembly, described further herein.

Although tray-type guide member 10 and conduit 11 can be connected in any suitable manner, as illustrated hereinafter, they constitute, in preferred practice, a single unit of integral construction, as shown. Thus in the embodiment shown, conduit 11 and guide member 10 as an integral unit can be fabricated by cutting a relief from one end of a tube, or pipe, member along a suitable circumference say of from about 180 to 300. Regardless of whether conduit 11 and guide member 10 are of integral construction, guide member 10 is of shape and is secured to conduit 11 to sequentially receive the axially moving seismic charge assemblies from conduit 11 and guide them in a line of continued forward travel, maintained under force of fluid pressure as further described herein, toward wheel member 12. In a now-preferred form, the inner wall 10a of guide member 10 is substantially coplanar with an adjacent inner wall portion of conduit 11 to facilitate travel of the seismic charge assembly from conduit 11 onto guide member 10.

Wheel member 12, in combination with guide member ID, is spaced from the forward end 13 of conduit 11 in a plane substantially codirectional with the path of forward travel of the seismic charge assembly on guide member 10; and is spaced from end 13 of conduit 11 so that the distance of its rim portion closest to conduit 11 is greater than the length of the particular seismic charge assembly, say from 1.1 to 1.3 times the length of the assembly, to provide a gap G between forward end 13 of conduit 11 and the rearward end of the seismic charge assembly when ready for pivotal travel from guide member 10 as described hereinafter.

Wheel member 12 is rotatably supported at its hub by support pin 14, secured to end 16 of L-shaped bracket 17, of which one leg 17a extends across the forward end of guide member 10 and the other leg 17b extends along the exterior wall of guide member 10 and is secured thereto by screwbolt members 19. Wheel member 12, when supported as above described, is disposed across the forward end of guide 10 sufiiciently to intercept the forward travel of the seismic explosive charge assembly on member 10 and contact a portion of its rim, facing conduit 11, with a percussionsensitive portion of the charge assembly, for effecting percussion initiation of the charge. Wheel 12 is advantageously of diameter sufficient for it to extend across the entire projected end of conduit 11, as further illustrated with reference to the end view of FIG. 1A. However the total shadow area of wheel member 12, and its associated support structure including arm 17a, i.e. the total area filled by that combined structure, is sufficiently limited to facilitate linear flow of water, or other driving fluid from conduit 11, around it to facilitate guidance and support of the charge assembly along its path of forward travel on guide member 10. Wheel member 12, and the percussion-sensitive portion of the charge assembly are preferably positioned so as to be disposed in the central portion of the path of forward travel of the charge assembly.

Although wheelmember 12 is now preferred structure for contacting the explosive charge assembly for percussion initiation, any suitable contacting means can be utilized to intercept forward travel of the seismic charge assembly and cause percussion initiation of same, on guide member 10. In preferred practice the contact means also serves as a pivot for pivotal travel of the percussion-initiated assembly from the firing device.

Although the inside diameter of the conduit 11 of FIG. 1 can be constant, it is often advantageous that at least a rearwardmost end portion thereof be tapered in a forward direction to facilitate arrest and positioning of the charge assembly for conveying it to the guide member I0. Also, at any given velocity of fluid inlet flow into the conduit (see FIG. 1B, conduit 11') an increase in fluid velocity takes place as the taper is continued to thus impart additional momentum to the moving charge assembly for the percussion initiation. Thus, referring to FIG. 1B, conduit 11 is the same as conduit 11 of FIG. 1 except that the inside diameter of rearwardmost end section 11a of conduit 11' is greater than that of the remaining forward section 11b and is tapered along its inner wall lla' down to the inside diameter of the forward section 1117. The tapered portion 11a generally extends from about one-fourth to one-half the length of the conduit 11.

An alternate embodiment of means for connecting guide member 10 and conduit 11 of the device of FIG. 1 is shown in FIG. 1C in which like parts of FIG. 1 are shown by like but primed, index numbers. Referring to FIG. 1C, a guide tray 10' and a conduit 11" can be separately secured in position by a support plate 21 extending along, and secured by screwbolts 22 to the exterior surface of each of the emplaced members 10' and 11''. A wheel member 12' assembly is secured in position by an L-shaped bracket 17 at leg l7a, the leg 17b being secured to the exterior wall of tray member 10' by screwbolts 23.

A now-preferred delayed percussion-initiatable charge assembly to be fired, in accordance with the invention is illustrated with reference to FIG. 2. Referring to FIG. 2, seismic cartridge assembly 24 comprises elongated cartridge shell 26 with bottom end closure 27 and opposite, and top, wall closure member 28 spaced from open top end 29 to form a resulting recessed shell portion 31 in direct and unobstructed open communication with the outside of shell 26. End closure 28 contains passageway, or opening, 30 extending therethrough to directly communicate recess 31 and interior shell portion 32. Well member 33 extends closed end first through opening 30 into operative contact with seismic charge 34, of the NCN-type to support a percussioninitiatable primer device 38 in detonating relationship therewith; and is supported at its open end in wall 28 in watertight relationship therewith in any suitable manner, generally by support of an integral-lipped open end 36 thereof on the exterior surface of the wall closure 28, often on a recessed portion of wall 28, as illustrated.

Percussion-initiated primer assembly 38 extends into well 33, closed end 41 first, in detonating relationship with charge 34. Elongated primer shell 37 of primer assembly, or device, 38 contains a high explosive base charge 39 such as PETN, adjacent closed end 41. Wall or cap closure member 42 is disposed in any suitable manner on, and across, top open end portion 43 of shell 37 in closing relationship therewith. Ignition charge 44 in shell 37 is supported in confinement, in any suitable manner, on wall 42. Inasmuch as open end 43 is adjacent the ignition charge 44, and communicates charge 44, with the remainder of the components of the device it is also referred to herein as the ignition end 43 of shell 37.

Confined ignition charge 44 is any suitable ignition composition which ignites to produce a flame in response to compression resulting from force of percussion applied to the exterior surface of closure cap 42. Primer charge assembly 48 in shell 37 is inclusive of any suitable primer composition intermediate high explosive base charge 39 and ignition charge 44. Delay assembly 49, with delay fuse composition 51, intermediate primer assembly 48 and ignition charge 44 is of composition and design conventionally used in electric delayblasting caps, and is advantageously pressed in either layered or cored form. The particular delay fuse composition and the degree of press and dimensions thereof, determine the time of burning; and in most embodiments selection of a specific delay fuse composition and correlation of same with the remaining variables is such as to provide a delay time in the order of from about 0.5 to about 2.0 seconds.

Delay fuse composition 5] is ignitable in response to direct contact with flame emitted from ignition of ignition charge 44 and is spaced in such ignitable relationship therewith. The primer composition of assembly 48 is detonatable in response to heat and flame emitted from burning of delay fuse composition 51 and is disposed subjacent delay fuse 51 in detonating relationship therewith. High explosive charge 39 is detonated in response to detonation of the primer composition and is disposed subjacent primer assembly 48 in that detonating relationship.

In a primer device of a complete charge assembly with which the invention is concerned, the primer delay such as illustrated with reference to FIG. 2 and a base charge composition are advantageously those utilized as such in the blasting cap art, for example high explosive base charges such as pentaerythritol tetranitrate, pentolite, cyclonite, tetryl, RDX and cyclotol; primer charges such as diazodinitrophenol, lead azide and mercury fulminate; and delay fuse compositions such as lead oxide/boron (98/2), read lead/boron (98/2), barium peroxide/tellurium/selenium (40/40l), barium peroxide/tellurium (60/40). Confined ignition charges in the primer device include potassium perchlorate, lead styphnate, mercury fulminate, antimony sulfide and lead azide, and mixtures of such materials as are well known in the munitions art, and are preferably those often utilized as the primer charge in 0.22-caliber rifle cartridges.

In preferred practice, primer assembly 48 comprises a diazodinitrophenol wafer 48a pressed above, and superposed on elongated capsule 48b which extends within and substantially coaxially with shell 37 in closing, or near closing, relationship therewith. Capsule 48b is open at each end and is superposed on base charge 39 and contains a second diazodinitrophenol charge 48c of density lower than that of primer wafer 48c. Wafer charge 48a is of sufficiently high density to be ignitable in response to contact with flame from ignition of delay fuse composition 44 as above described and diazodinitrophenol charge 48c is of suflicient low density to be detonatable in response to heat developed by ignition of wafer charge 48a to thereby in turn cause detonation of base charge 39.

The primer device 38 of FIG. 2 is further illustrated with reference to the enlarged partial sectional views of optional embodiments thereof, of FIGS. 2A-B inclusive, in which like parts of FIG. 2 are shown by the same, but primed, index numbers and in which corresponding (though unlike) parts are shown by the same but lettered, index numbers. Referring to FIG. 2A, percussion-initiated primer 38 contains primer assembly 48 with high density diazodinitrophenol wafer charge 48'a, capsule 48b, lower density diazodinitrophenol charge 48'c, and base charge 39', as described with reference to FIG. 2. Delay assembly 49' comprises a suitable pressed delay fuse charge 51', such as BaO /Se/SE/ (40/40/20). FIG. 2B depicts the primer assembly 38 of FIG. 2 with reference to delay fuse assembly 49a which comprises a metal tube 50 as a closure in shell 37' such as one formed from lead, with a conventional pressed core delay fuse composition 51a.

FIGS. 2C and 2D, in which each lettered index number refers to a like, or to a corresponding, part of FIG. 2 identified therein by the same, but unlettered number, show optional percussion initiator means for primer device 38. With reference to FIG. 2C, the ignition end 43a of shell 37a is closed by a conventional rim-fired empty primed rifle cartridge casing 52 which includes end closure 42a with charge 440 for rim firing; and with reference to FIG. 2D the ignition end 43b of shell 37b is closed by conventional centerfired empty primed rifle cartridge casing 53 which includes end closure 42b with charge 44b for center firing. Shell casings 52 and 53 are of outside diameter sufficiently less, respectively, than the inside diameters of shells 37a and 37b to provide, in each instance, for an interference or friction fit of the casing closure in the primer shell.

Primer assembly 38 extends into primer well 33, percussion end 42 last, and terminates in detonating contact with main charge 34 in cartridge shell 26. Primer assembly 38 is preferably disposed entirely within cartridge interior 32 except to permit the primer end closure 42, at its exterior surface, to be at least flush with the exterior surface of the open end of well 33 in cartridge closure 28 and preferably to permit both primer closure 42 and the ignition charge 44 thereon to protrude from primer well 33 into recessed area 31 to facilitate application of percussion force by the pin assembly to the exterior of closure 42 for compression and ignition of the charge 44.

When utilizing an empty primed rim-fired or center-fired rifle cartridge case as an enclosure for the primer device 38, the rifle case portion can be of any desired length, such as in the order of about three-eighth inch; and from about 0.3 to 0.4 grain of the ignition charge is generally employed although the amount is variable dependent upon the particular ignition and primer assembly charges contemplated. The primer device, generally cylindrical as shown, is in most embodiments from about 2% to 3 inches in length by about 0.246 to 0.248 inch in diameter.

The amount of high explosive base charge 39 in an assembly 38 of FIG. 2 generally is greater than that utilized as base charge in a conventional No. 8 blasting cap. For example, the amount of PETN, as a base explosive charge 39 is generally in the order of from about 0.8 to 1.5 grams as compared with the conventional amount of 0.4 gram utilized as base charge in a No. 8 electric blasting cap. The amount of primer charge, e.g. charges 48a+48c of FIG. 2 is generally about the same as utilized in a conventional No. 8 blasting cap, being often from about 0.28 to 0.30 gram. The amount, degree of press and dimensions of delay fuse 51 is dependent on the correlation of those variables with the desired burning rate, from 0.3 to 0.4 gram of delay fuse composition often being utilized, whether of the pressed layer or core type.

The following, with reference to the drawings, is a tabulation of data exemplary, and further illustrative of a nowpreferred complete percussion-initiatable seismic charge assembly to be fired in accordance with firing mechanism, method, and system of the invention:

Primer Unit Metal Shell 37 Metal-cylindrical.

Length, inches 2.98. Diameter, inches:

Inside 0.22. Outside 0.24.

inches 0.48. Primer-Ignition 48:

Diazodinitrophenol,

grams 0.29.

Above capsule 48a) Pressed at 5,000 p.s.1. Below capsule (48c) Loose.

Base charge 39:

PETN, grams 1.5pressed at 6,500 psi.

Cartridge Unit Metal Shell 26 Metal-cylindrical.

Length, inches 4.68. Diameter, inches:

Inside 2.04.

Outside 2.09. Recess 31, inches,

length 0.41.

NCN Charge 34:

Weight, grams 250. Length, inches 3.27. Diameter, inches- 2.04.

Composition, wt.

percent:

Ammonium nitrate 78.7. DNT 5.0. Fuel oil 1.5. Particulate aluminum 14.8.

*Pb/Sn, 85/15.

In preferred practice, the main charge of the complete seismic charge assembly is a nitrocarbonitrate by which term (nitrocarbonitrate) is meant there are no sensitizers or other ingredients in that composition which are high explosives, and the mixture will not detonate with a No. 8 blasting cap when packed for shipment.

Nitrocarbonitrate-type explosive charges, as iswell known,

contain at least one inorganic oxidizer salt, a fuel, and a suitable sensitizer together with various other well-known ingredients such as one or more of an antiset agent, waterrepellant coating material or the like. Most often ammonium nitrate is the chief inorganic oxidizer salt ingredient alone, or with sodium nitrate or other suitable inorganic oxidizer salts. Further exemplary of inorganic oxidizer salt that can be used alone or together with ammonium nitrate as the inorganic oxidizer slat ingredient of nitrocarbonitrates are alkali metal and alkaline earth metal nitrates and perchlorates (including ammonium) as for example sodium nitrate, magnesium nitrate, calcium nitrate, potassium nitrate, barium nitrate, sodium perchlorate, ammonium perchlorate, calcium perchlorate and magnesium perchlorate. Well-known sensitizer materials for nitrocarbonitrates include DNT and particulate aluminum alone or together with suitable fuels such as, for example, powdered coal, fuel oil, ferrosilicon, ferrophosphorous and the like. The following formulations (weight percent bases) are further illustrative of nitrocarbonitrate-type charges above described and now preferred in practice of invention.

A B C D E F Ammonium nitrate 1 82 91 86 79 91 78 Sodium nitrate- 10 DNT 2 5 5% 5 5 Aluminum 6 10 12 Fuel oil 4 1% 1 Ferrosilicon. 8 Ground coal. 4 4 4 4 4 E (loi lnd prills, formulations A, B, C and D; granular, formulations an 1 Dinitrotoluene oil, formulations B, D and E; solid dlnltrotoluene, formulation F.

! Flake, formulations A and C; granular, formulation F.

, advantageously utilized as such, in an amount of from 75 to 90 percent together with from about 1 to 15 percent sodium nitrate. Now-preferred sensitizer components are DNT oil, DNT solids, particulate aluminum, and mixtures of any two or more thereof, in a total amount of from about 5 to percent, at least about 5 percent of the particulate aluminum being flake. Also, in preferred practice, the nitrocarbonitrate charge contains, as a separate fuel component, fuel oil, ground coal, granular aluminum or a mixture of two or more thereof, in any suitable amount, generally from 2 to 15 percent.

When referring herein to small nitrocarbonitrate seismic charges, it is meant those which generally have a weight from If; to 3 lbs. and a diameter of at least one-half inch and usually not exceeding about 3 inches. However, in some offshore exploration areas, a nitrocarbonitrate charge of any suitable size can be utilized and indeed the explosive charge can be a dynamite or other suitable high explosive. In FIG. 3, a firing device of FIG. 1 is shown in perspective, together with a percussion-initiatable seismic charge assembly moved into emplacement therein for percussion initiation and pivotal travel for detonation in the seismic test zone. As illustrated in FIG. 1 and 3, the detonation of the seismic charge is accomplished outside the firing system so as to preclude damage to the firing device that would be caused by force from the resulting detonation if the charge were detonated while still within the firing mechanism.

Referring to FIG. 3 in which like parts of FIGS. 1 and 2 are referred to by the same but parenthesized index numbers, firing mechanism 9 is a unit of integral construction of conveyor conduit 11 and tray member 10 formed by cutting a relief from one end of a pipe member along its circumference at say The length of unit 9, Le. the sum of the lengths of units 10 and 11 is often in the order of from 16 to 18 inches, the length of tray member 10 being often from 4% to 5 inches but necessarily greater than that of the main cartridge assembly 5 to permit spacing 6 between the rear end 27 of assembly 5 for pivotal travel from tray 10 as described more fully hereinafter.

As shown in FIG. 3, when elongated charge assembly 5 is moved into conveyor conduit 11 from the delivery hose 6, recessed percussion end 31 first, it (assembly 5) is conveyed axially through conduit 11 to adjacent guide tray 10 and into an axial path of forward travel l0'a on guide tray 10 until it is entirely outside conveyor conduit 11 with end 27 spaced from conduit 11 for pivotal travel after initiation. Wheel pin 12 is supported in the path of travel of assembly 5 so as to intercept forward travel of assembly 5 and contact the percussionsensitive end 42 thereof along a portion of its rim 12a to cause initiation of assembly 5 by compressive force of the resulting impact.

In the operation of the firing device of the invention, as further illustrated with reference to FIG. 1, a complete charge assembly, such as one illustrated with reference to FIGS. 2- -2D is transferred from a supply source under force of fluid pressure, into conveyor conduit 11, percussion end first into and conveyed through conduit 11 to guide member 10 and into a path of continuous forward travel on member 10 for the percussion initiation. The charge assembly continues forward travel on tray 10 under force of the water pressure and guided along that path of travel not only by sidewall portions of the member 10 but by force of flow of water (in the waterimmersed device) displaced by the forward-traveling charge assembly, which passes the firing wheel by virtue of the small shadow area of the wheel relative to the water stream. The charge assembly is guided on tray 10 in alignment with the rim of wheel 12. The charge assembly in its continued forward travel on tray 10 then contacts the percussion-sensitive portion thereof with a rim portion of wheel 12 for initiation resulting from force of impact in response to the driving force of the water. Upon percussion initiation, burning of the delay fuse proceeds to delay detonation of the base charge in the primer device to provide time for pivotal travel of the thusinitiated assembly, about the wheel pin or a pivot, from the tray member for detonation at an external point.

As the charge assembly comes to a stop upon contacting the wheel pin, driving fluid still flowing through conduit 11 flows away from the device through the rear spacing, or gap G, which unbalances the assembly unit and causes it to pivot about wheel pin, as the pivot point, and thus pivotally travel from the device, as illustrated with reference to FIG. 1. The cycle is then repeated, generally as the device is towed through the underwater seismic exploration area.

System and method of the invention are diagrammatically illustrated with reference to FIG. 4. Referring to FIG. 4, charge assembly storage 54 on deck 60 of towboat 61 provides for storage of a supply of percussion-initiatable charge assemblies such as of FIGS. 2--2D generally with rim-fire percussion means illustrated with reference to FIG. 2C. Charge assemblies from storage 54 are sequentially loaded into cartridge loader, or breech block assembly, 56 through hinged top 57. Water pump system 58 supplies water under pressure via discharge line 59 to loader 56 at the rear 55 thereof. Reel 65 on boat deck 60 supports a streamer cable described hereinafter. Flexible hose 62 extends from loader 56 to a conveying conduit of a firing device of the invention, as for example conduit 11, of FIG. 1 for sequential delivery of the percussioninitiatable charge assemblies for initiation and firing as the firing device is towed by boat 61 through the seismic exploration area. Water, under pressure, from pump system 58 forces travel of each charge, from loader 56 through hose 62 and into and through the firing device as described hereinabove.

Streamer cable assembly 63, of conventional design, comprises a hydrophone cable 64 and tow cable 64; cable 64 contains a plurality of hydrophone groups 66 integrally connected in spaced-apart relationship along the entire length thereof, and is connected at one end by tow cable 64 to reel assembly 65 for reeling and towing. Suitable well-known means (not shown) are associated with streamer cable assembly 63 to stabilize its position at a predetermined depth in the body of water; and suitable means (not shown) for communicating hydrophone groups 66 with recorder means on the boat deck, extend from within cable 64 along side tow cable 63 via reel assembly 61.

In practice, streamer assembly 63 is towed through the water body during which time the seismic charges are detonated outside the system at predetermined intervals, and distances, to initiate seismic shock at the predetermined points in the test area. Disturbances produced by the shot, or shock, are detected by the hydrophone groups which convert those pressure variations into electric signals which are then communicated to the boat for recording.

FIGS. 7 inclusive, and auxiliary views, illustrate additional embodiments of charge-assembly-conveying means, percussion contact means, and means for directing the initiated explosive charge from the firing device.

Referring to FIG. 5, explosive charge assembly conveyor conduit 71 is adapted to receive elongated charge assemblies 4 and then convey them through forward end 73 into a continuous path of forward travel on tray-type guide member 72, immediately forward of conduit 71. Guide member 72, which can be the same as guide member of FIG. 1, is a traytype member for sequentially receiving the percussioninitiatable seismic charge assemblies from conduit 11 for guiding each charge assembly along a line of continuous forward travel from conduit 71 to contact assembly 74 at or near the forward end 70 of guide member 72.

As similarly illustrated with reference to FIGS. 1 and 3, charge assemblies 4 are moved by force of fluid (generally water) pressure from conduit 71 to guiding means 72 and then forwardly into contact with means 74 for the percussion initiation. Contact, or pin-type assembly 74 is supported across guide 72 at or near the forward end 70 thereof. In the embodiment shown, assembly 74 comprises partial disc member 76, and concave edge or rim 77 thereof. Concave edge 77 faces conduit 71 so as to contact the percussionsensitive portion of charge assembly 4 on guide 72 in the same manner as illustrated with reference to contact of wheel member 12 and charge assembly 5 of FIG. 1. Partial disc 76, in a plane parallel to the path of forward travel of charge 4, is secured in any suitable manner (not specifically shown) such as by weld, to arm 78 of bracket 79, of which arm 81 extends along the exterior wall of guide 72 and is secured thereto by screwbolt 82, thereby supporting arm 78 and contact member 74 in operating position, as shown. It is necessary in practice of the embodiment of FIG. 5 that the pin assembly 74 and support bracket 78, close an area at least one-tenth the crosssectional area of conduit 71 and preferably from one-fourth to one-half, or somewhat greater if desired, as further illustrated with reference to the end view of FIG. 5, shown in FIG. 5A. Such dimensioning of the contact assembly is necessary in order that the shadow area of the combined arm 78 and contact member 74 be sufficient to partially deter flow of fluid from conduit 71 and guide 72, through front end 70 of guide 72, in order that pressure from flow of driving fluid from conduit 71 be sufficiently high to prompt substantially lateral travel of charge assembly 4, as indicated by arrow a, from guide 72 for subsequent detonation. In some instances, dependent on the shadow area of the pin assembly 74 and support arm 78, and size of gap G, a combination of lateral and pivotal travel of the initiated charge from the firing device may result. Thus if gap G is sufficiently large, say as gap G of FIGS. 1 and 3, and the shadow area in the above-described range (at least one-tenth, preferably one-fourth to one-half, or

somewhat greater) of cross-sectional area of conduit 71 is sufficiently low, some pivotal travel, the same as that of FIGS. 1 and 3, may occur, dependent on the particular combination of gap and shadow area conditions. Gap G is the distance between the end 73 of conduit'7l and the rear end 27 of assembly 4 when the latter has reached its forward point of travel for percussion initiation. Gap G is utilized to provide additional space through which the initiated charge assembly can be directed for subsequent detonation. The embodiment of FIG. 5 differs from that of FIG. 1, the latter accomplishing pivotal travel, entirely, of the initiated charge assembly for the subsequent detonation.

Optionally, bypass conduit 83 is outside conduit 71 with one end in open communication with the interior of conduit 71, and the other end extending through a wall of guide member 72. Conduit 83 serves to deliver driving fluid under pressure from conduit 71, into guide 72 against the charge assembly after percussion initiation of same to facilitate the lateral travel of charge assembly 4.

In the operation of the embodiment of FIG. 5, force of driving fluid introduced under pressure into conduit 71 moves the assembly 4 along its forward path of travel on guide 72 under sufficient momentum for contact of the charge assembly with the pin assembly 74 for the percussion initiation. However flow of driving fluid from end of guide 72 is less than that of the driving fluid in the embodiments of FIGS. 1 and 3, due to the smaller shadow area of the wheel assembly of FIG. 1. Hence the momentum of the charge assembly 4 is sufficiently low to permit its lateral travel through the open portion of tray 72 in response to force of fluid from conduit 71 with or without flow of same through conduit 83, after forward travel of the charge assembly is terminated at the time of impact. As shown, the charge assembly 4 has impacted pin assembly 74, and is percussion initiated and in process of lateral travel from guide 72 and hence from the firing device for detonation outside the system.

FIG. 5 further illustrates percussion-initiatable charge assembly 4 differing from charge assembly 5 of FIGS. 1 and 3, by absence of a top-recessed portion, e.g. recess 31 FIG. 2, which, as above described, is used advantageously for safety reasons, although it does facilitate initial contact with a wheelor disc-type contact member such as of FIGS. 1, 3 and 5. In lieu of a curved contact surface 77, of assembly 74, a straight, edge-type surface can be utilized as further illustrated hereinafter.

Referring to FIG. 6, conduit 84 is the sole means for conveying the charge assemblies 4' for percussion initiation. The tray-type guide member structure illustrated hereinabove is not required in practice of the embodiment of FIG. 6. Conduit 84 by force of fluid pressure, as illustrated with reference to conduit 11 of FIG. 1, conveys charge assembly 4, which is the same as assembly 4 of FIG. 5, along a forward path of travel, as indicated by the arrow b, for impact with contact means, or pin-type assembly, 86 and for direction, after percussion initiation, through forward end of conduit 84 for subsequent detonation outside the device. In this embodiment, travel of the percussion-initiated assembly is linear in contrast with lateral travel (FIG. 5) and pivotal travel (FIGS. land 3).

Conduit 84 contains slot 87 extending through an end wall section 87 thereof, i.e. formed by an opening entirely through the wall at the rearward point of end section 87 and extending along the entire end section 87 through the forward end 90 thereof. However slot 87 need not forwardly extend in the entire end section 87.

Slot 87 extends substantially parallel to the longitudinal axis of conduit 84. Elongated contact member, or pin-type assembly, 86 is pivotally secured at an intermediate point 88 thereof by suitable pin means 88 to conduit 84 within the confines of slot 87 so as to pivotally move in an axial direction in conduit 84. Slot 87 and member 86 are dimensioned so that member 86, when extending into conduit 84 through slot 87, is pivotally movable counterclockwise about pin 88' into slot 87, the latter further illustrated with reference to FIG. 6A which is a cross-sectional view of the embodiment of FIG. 6 in an advanced state of operation, and in which all like pans of FIG. 6 are designated by like index numbers. Detent, or block, 89 secured by screwbolt 89' to the exterior of conduit 84, is positioned proximate to pin member 88', so as to block clockwise pivotal movement of assembly 86 beyond that which allows extension of the lower arm portion 86' across the path of forward travel of the charge assembly in conduit 84. Any suitable biasing system 91 is adapted to bias assembly 86 against counterclockwise pivotal movement, when in its clockwise most position, so as to impart requisite rigidity to assembly 86 for its function as contact means for the percussion initiation.

One suitable bias system 91 comprises bracket 92, secured to the exterior of conduit 84 by screwbolt 93, and arm 92' thereof extending along a path encompassing contact assembly 86, and terminating forwardly of pin 88'. Arm 92 connects at its forward end 94 with spring member 96 in turn attached to top end 86" of assembly 86. Tension on spring 96 is adjusted so as to bias assembly 86 in operating position, i.e.

with the am 86 thereof extending across the path of forward travel of the charge assembly in conduit 84, as shown.

At least a portion of the surface of arm 86' facing rearward end 80 of conduit 84 is positioned so as to contact the percussion-sensitive portion of the charge assembly 4' for the requisite contact for initiation. The surface portion 97 of arm 86' is preferably edged to form edge 98 which is that portion of arm 86' positioned for direct impact with the percussionsensitive portion of assembly 4. Edge 98 is advantageously a knife-edge-type structure.

In the operation of the embodiment of FIG. 6, the balance of momentum of the forwardly moving assembly 4' and the inertia of the firing mechanism 86 is sufiicient to provide firm contact of the charge assembly and assembly 86 for the necessary percussioninitiation impact and also to then cause the assembly 86 to move counterclockwise about its pivot 88' into slot 87 to thereby permit travel of the percussion-initiated charge linearly from the firing device for the detonation outside, as further illustrated with reference to FIG. 6A. FIG. 6B is a view along the line 6B-6B of FIG. 6 more specifically illustrating slot 87 and firing assembly 86 structure of FIG. 6. FIG. 6A is a sectional view of the embodiment of FIG. 6, in an advanced state of operation, and in which like parts of FIG. 6 are designated by like numbers.

Referring to FIG. 7, charge assembly conveyor conduit I01 conveys charge assemblies 4" to tray-type guide assembly 102 at the forward end 103 of conduit 101 and into a line of continuous forward travel on guide member 102 for percussion initiation by contact with contact member 104 supported on arm 105' of bellcrank lever assembly 105 for percussion initiation and for direction by bellcrank lever assembly 105 from the device for detonation outside the system. In this embodiment, travel of the percussion-initiated charge assembly from the firing device is directed by a sweeping action of the bellcrank lever about its pivot which is in turn actuated by momentum of the charge assembly as it moves into contact therewith.

Guide member 102 can be the same as guide members 10 and 72 illustrated above. Guide member 102 contains a slot 106 in the wall thereof formed by an opening through a rear wall portion of tray 102 and extending substantially parallel to the path of continuous travel of the assembly through the forward end of the guide member 102 as further illustrated with reference to FIGS. 7A and 7B in each of which like parts of FIG. 7 are designated by like numbers.

Bellcrank lever 105 is pivotally secured to guide member 102 by suitable pin support means 108 at substantially the forward end of slot 106, within the confines of slot 106, and so as to be pivotally movable about its pivot point 107 codirectionally with the longitudinal axis of conduit 101.

Lever arm 105" of bellcrank lever 105 has a length at least as great as the dimension (length, if elongated) of the charge assembly 4", when that dimension is measured on the path for forward travel in guide member 102, and is movable into and out of slot 106 about the pivot point 108. When arm 105" is entirely within slot 106, the other arm of bellcrank lever 105, i.e. arm 105' is disposed across the path of forward travel of the charge assembly in guide member 102 so as to face conduit 101.

Bellcrank lever 105 is positioned to pivotally dispose arm 105" entirely within slot 106 and so that arm 105', at that time, extends across, and faces the inner surface thereof toward conduit 101 and hence toward the forward path of the assembly 4' in guide member 102.

Any suitable means on the inner surface of arm can be utilized as a surface for contacting assembly 4" for the percussion initiation. In preferred practice, an edged elongated member 109 is disposed on the surface 100 of arm 105", i.e. facing conduit 101, with edge portion 104 thereof aligned for contact with the percussion-sensitive portion of charge 4" for contact for the percussion initiation. Lever arm 105" is biased in its position within slot 106 by any suitable means such as spring-biasing assembly 109 comprising bracket 111 secured in any suitable manner such as by weld 112 to the exterior of conduit 101 and connecting with spring 113 at one end which in turn connects with arm member 105".

Base 1 10 of bracket 111 is disposed over slot 106 and serves as detent means to preclude clockwise pivotal travel of arm 105" through slot 106 to the exterior of guide member 102. In another embodiment (not shown) guide member 102 contains a slot of the same dimensions, and function, of slot 106, except that it (not shown) extends along, and within, the inner wall portion of guide 102, thereby precluding pivotal travel of arm 105" through the guide wall member.

In the operation of the embodiment of FIG. 7, a forwardly moving charge assembly 4" upon contacting surface 104 for delayed percussion initiation, by force of its momentum against surface 104 and pressure of water flowing from conduit 101 through gap G", similar to gap G of FIG. 5, upon termination of forward travel of the assembly 4, overcomes the biasing action of spring 113 to cause crank lever 105 to pivot counterclockwise with resulting sweeping or pivotal action against charge assembly 4" and direction of assembly 4 outside the device for the detonation, as further illustrated with reference to FIG. 7B, which is a cross-sectional view of the embodiment of FIG. 7 in an advanced state of operation and in which all like parts of FIG. 7 are designated by like numbers.

Although method and system of the invention illustrated with reference to FIG. 4, each involves operation of a single firing device from a boat deck, it is often advantageous from the standpoint of practicability to have a plurality of the firing devices available for such operation completely independently of the other. Availability, and use of a plurality of such independently operated firing devices provides for (l) a routine maintenance of one device, and associated system, during on-time" of another, without interrupting continuous profiling operations, (2) the operation of a plurality of the devices simultaneously for increased seismic energy; and (3) operation of the devices, alternately, to meet high multiplicity requirements.

By way of example, 187 complete percussion-initiatable seismic charge assemblies were sequentially fired in an underwater seismic zone in a firing device of the invention, in accordance with method and system of FIG. 4.

The complete seismic charge assemblies thus fired were those specifically illustrated with reference to FIG. 2 in which the percussion-sensitive end closure element 42 was an empty primed rim-fired cartridge casing for 0.22 caliber short ammunition, (assembly 52 of FIG. 2C) and the delay fuse assembly 49 was a pressed layer of fuse composition 51, further illustrated with reference to layer 51 of FIG. 2A. Each of the complete assemblies fired was in accordance with all specifications set forth in the tabulation of exemplary charge assembly specifications at page l8 hereinabove.

The firing device, in which the assemblies were fired, was of integral construction and was that shown in FIG. 1 except that it contained a tapered rear inner wall portion shown in FIG. IB. The overall length of the firing device was 16.6 inches, the length of the charge conveyor conduit (conduit I1, FIG. IB) was l3.5 inches with the rear tapered portion (wall lIa, FIG. 18) extending 8 inches from a 3-inch inside diameter to a constant inside diameter of 2.280 inches; and the tray member (tray I0, FIG. I) was 5.1 inches in length and was formed in an arm of about I80". The wheel-type pin member (pin I2, FIG. I) was a disc of about 2 inches in diameter rotatably supported at its hub by bracket means illustrated in FIG I.

The charge assemblies were sequentially loaded on boat deck and transported to the firing device in accordance with system and procedure of FIG. 4 via a 3-inch inside diameter by 80 feet flexible delivery hose (conduit 62, FIG. 4) connecting with a breech block (loader 56, FIG. 4) and extending into the underwater seismic area at a depth of about 25 feet, and there connecting with the firing device under tow by the boat at a speed of from 5 to 7 knots.

Each complete assembly was moved by force of water pressure (system 58, line 59, FIG. 4) through the delivery hose into and through the firing device. The transpon time, i.e. time for travel of each charge from the boar deck to the firing device and percussion initiation of same, was in the order of from 5.7 to 6 seconds, and the duration between actual loadings was in the order of 10 to 12 seconds.

Each assembly delivered to the firing device was percussion initiated therein and then, during the delay period, was pivotally directed from the device for the detonation, which took place in each instance, outside the device, as evidenced by no damage imparted to the firing device by force of the resulting detonation. The delay period for each firing, regulated by selection and amount of delay fuse composition, was 1.0 second.

It will be evident to those skilled in the art, various modifications can be made or followed, in light of the foregoing disclosure and discussion without departing from the spirit or scope of the disclosure or from the scope of the claims.

Iclaim:

I. A firing device for initiating delay-type percussion initiatable explosive charge assemblies and then directing the initiated assemblies for detonation away from the firing system, comprising means for sequentially conveying said charge assemblies into, or along, a path of continuous forward travel for percussion initiation of same; means in combination with said conveying means at a forward point on said path of travel for sequential contact, while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same by force of resulting impact; and means for sequentially directing the thus-initiated charge assemblies away from said firing device during said period.

2. In a firing device of claim I, open means for guiding said charge assemblies along said path of continuous forward travel; means for conveying said charge assemblies sequentially to said open guiding means and then into said path of continuous forward travel; and said means for contact supported at a forward point on said guiding means.

3. In a firing device of claim 2, said means for contact spaced from said conveying means a distance greater than the dimension of each said charge assembly contacted therewith, as measured on said path of travel, and forming a pivot for directing pivotal travel of the initiated charge assemblies from said device.

4. In a device of claim 2, a conduit as said conveying means; and a tray member, as said open guiding means, at one end of said conduit.

5. In a firing device of claim 4, said conduit and said tray member constituting an integral unit of construction formed by cutting a relief from one end of a tube.

6. In a firing device of claim 4, at least a portion of a rimmed-wheel-type member, as said means for contact, supported in a plane substantially codirectional with said path of travel, and a rim portion thereof facing said conduit so as to contact a percussion-sensitive portion of each of the forwardly traveling charge assemblies.

7. In a firing device of claim 4, a stationary contact member, as said means for contact, extending across at least a portion of said path of forward travel, and a surface portion thereof facing said conduit so as to contact a percussion-sensitive portion of each of the forwardly traveling charge assemblies, for said impact; and said stationary contact member disposed in an area across said path of forward travel equal to at least about one-tenth the cross-sectional area of said conduit.

8. In a firing device of claim 7, a fluid bypass extending, outside said conduit and tray members, from open communication with the interior of said conduit through a wall of said tray member intermediate said stationary contact member and said conduit.

9. A firing device of claim 8, wherein said bypass extends through said wall at a point spaced from said stationary contact member a distance not more than about two-thirds of the dimension of each said charge assembly measured on said path of travel.

I0. In a firing device of claim 7, a ridged surface as said surface portion, and the ridge thereof facing said conduit for said contact.

11. In a firing device of claim 4, said tray member containing a slot extending along its inner wall portion codirectionally with said path of forward travel; a bellcrank lever pivotally secured at its pivot point to said tray member; an arm of said bellcrank lever having a length at least as great as the dimension of said charge assembly measured on said path, and movable into and out of said slot about said pivot, and the other arm disposed across said path of forward travel so as to face said conduit when the first said arm is within said slot; a surface portion, of the last said arm member when disposed across said path, facing said conduit, so as to contact a percussion-sensitive portion of each said forwardly traveling charge assembly for said impact; and means for biasing the first said lever arm entirely within said slot.

12. In a firing device of claim 11, a ridged surface, as said surface portion, and the ridge thereof facing said conduit for said contact.

13. In a firing device of claim 1, a conduit for sequentially conveying said charge assemblies for said percussion initiation, and said conduit containing a slot formed by an opening, through a wall of an end section thereof, and extending substantially parallel to the longitudinal axis of said conduit through said conduit end; an elongated member, as said means for contact, secured at an intermediate point, to said conduit within the confines of said slot and pivotally movable, about said point, counterclockwise into said slot and clockwise from within said slot to a position extending through said slot into said conduit and across said path of forward travel; means for blocking clockwise travel of said elongated member farther than above described; means for biasing said elongated member in its position of farthest clockwise travel; and when said elongated member is blocked in said farthest position of travel, a surface portion of said elongated member facing the rearward end of said conduit so as to contact a percussion-sensitive portion of said charge assembly, while traveling in said path of forward travel, for said impact.

I4. In a firing device of claim 13, a ridged surface as said surface portion, and the ridge thereof facing said conduit for said contact.

15. A firing device for initiating elongated delay-type percussion-initiatable explosive charge assemblies, and then delivering the initiated charge assemblies for detonation outside the firing system, comprising a conduit, and a tray member extending from one end thereof; said tray member being adapted to sequentially guide such charge assemblies along a path of continuous forward travel thereon for percussion initiation of same, and for pivotal travel of the thus-initiated charge as described hereinafter; said conduit being adapted to sequentially convey such charge assemblies to said tray and into said path of forward travel; impact means secured to said device and disposed in said path of forward travel for sequential contact with each said charge assembly to cause percussion initiation of same by force of resulting impact; said impact means being spaced as, and forming, a V

pivot for directing pivotal travel of said charge assembly from said tray member after said impact.

16. A firing device of claim 15, wherein said pivot is spaced from said conduit a distance of at least about 1.2 times the length of each said charge assembly contacted therewith.

17. A firing device of claim 16, wherein said conduit and tray members constitute a unit of integral construction.

18. In a firing device of claim 17, said conduit being tapered, along a portion of its length, from its rearwardmost end.

19. A firing device of claim 17 for initiating an explosive cartridge assembly containing a primer element having an empty primed rifle cartridge case as a percussion-initiator means therefor; said rifle casing being disposed at one end of said charge assembly, and said impact member disposed in said path of forward travel so as to contact said empty primed rifle casing, when said charge assembly is conveyed, percussion end first, into said path of travel, to cause percussion initiation of same by force of resulting impact.

20. A firing device of claim 19 wherein said impact member is at least a portion of a rimmed-wheel-type member positioned so as to directly face a rim portion thereof against said path of travel for contact of said rim portion with the empty primed rifle cartridge case element of each said charge assembly to cause said percussion initiation.

21. A firing device of claim 20 wherein said empty primed rifle casing is rim fired.

22. A firing device of claim 20 wherein said empty primed rifle casing is center fired.

23. A firing device of claim 20 wherein said impact member is a complete wheel and is rotatably supported at its hub.

24. A seismic exploration method, wherein complete delaytype percussion-initiatable seismic charge assemblies are initiated, emplaced, and fired in an underwater zone to provide energy for a seismic record, said method comprising sequentially conveying a plurality of said charge assemblies into, or along, a path of forward travel in said underwater zone; sequentially impacting said assemblies concurrently with said forward travel to percussion initiate same; and during the period of said delay, sequentially directing travel of the thus-initiated charge assemblies away from the zone of said percussion initiation into an adjacent area in said underwater zone for detonation.

25. A seismic exploration method wherein complete delaytype percussion-initiatable seismic charge assemblies are initiated, emplaced, and fired in an underwater zone to provide energy for a seismic record, said method comprising sequentially delivering a plurality of said charge assemblies under force of fluid pressure into a charge-conveying means of a firing device in said underwater zone; said firing device comprising (1) means, as said charge-conveying means, for sequentially conveying said charge assemblies into, or along, a path of continuous forward travel for percussion initiation of same; (2) means in combination with said conveying means at a forward point on said path of travel for sequential contact,

18 while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same b force of resultin im act' and (3) means for uentiall directing the thus-irfitiate d charge assemblies frorfi aid firing device during the period of said delay; regulating said fluid pressure so as to impart sufficient force of impact for said percussion initiation with concomitant initiation of said charge assemblies and subsequent delay of priming action thereof, whereby during the period of said delay, travel of the thus-initiated charge assemblies is sequentially directed away from the zone of said percussion initiation into an adjacent area in said underwater zone for detonation.

26. in a method of claim 25, sequentially delivering a plurality of said charge assemblies into a charge-conveying means of a firing device in said underwater zone; said firing device comprising (l) open means for sequentially guiding said charge assemblies along said path of continuous forward travel; (2) means, as said charge-conveying means, for conveying such charge assemblies sequentially to said guiding means and then into said path of continuous forward travel; and (3) means in combination with the guiding means supported at a point on said path of travel for contact with said charge assemblies to cause said percussion initiation, and the last said means being spaced from said charge-conveying means as, and forming, a pivot for directing sequential pivotal travel of the thus-initiated charges from the zone of said initiation into an adjacent area in said underwater zone; whereby the thus-initiated charge assemblies are sequentially and pivotally directed into said adjacent area for detonation.

27. A system for generating seismic disturbances in a body of water which comprises a movable platform; means on said platform for storage of percussion-initiatable seismic explosive charge assemblies; a firing device, as a submersed firing station, comprising (1) means for sequentially conveying said charge assemblies into, or along, a path of continuous forward travel for percussion initiation of same; (2) means in combination with said conveying means at a forward point on said path of travel for sequential contact, while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same by force of resulting impact; and (3) means for sequentially directing the thus-initiated charge assemblies away from said firing device during the period of said delay; a delivery conduit connecting from said platform with said conveying means of said submersed firing station; fluid-pressure-generating means on said platform connecting with said delivery conduit for supplying force of fluid pressure for sequentially moving said charge assemblies from said platform through said delivery conduit to said conveying means, and into said impact.

28. A system of claim 27 in which said firing device comprises l open means for sequentially guiding said charge assemblies along said path of continuous forward travel; (2) conduit means for conveying said charge assemblies sequentially to said guiding means and then into said path of continuous forward travel; and (3) means in combination with said guiding means at a forward point on said path of travel for sequential contact, while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same by force of resulting impact, and for directing the thus-initiated charge assemblies from said guiding means; and said fluid-pressure-generating means connecting with said delivery conduit for sequentially moving said charge assemblies from said platform to said conveying means and then into and along said path of travel on said guiding means, for said impact.

29. A system of claim 28 wherein, in said firing device, said means for contact is spaced as, and forms, a pivot for directing pivotal travel of the initiated charge assemblies from said device.

Dated Aoril l3 1971 Patent No. U.S. 3,574,298

Inv n Richard R- Larson above-identified patent at error appears in the ted as shown below:

It is certified th e hereby correc and that said Letters Patent er I" IN THE SPECIFICATION Column 2, line 43 after "during" insert --the pe of; delete "period" and substitute -delay--.

Column 3, line 7 after "of" insert --delay type- IN THE CLAIMS "during" insert the last line, after and substitute Claim 1,

- delete "period" -the period of,

Claim 27 line 3 after "of" insert -de1ay type Signed and sealed this 25th day of January 1972.

SEAL) Attest: EDWARD M.FLI12TCHER,JR. ROBERT GOTTSCHALK Commissioner of Patents Attesting Officer 

1. A firing device for initiating delay-type percussioninitiatable explosive charge assemblies and then directing the initiated assemblies for detonation away from the firing system, comprising means for sequentially conveying said charge assemblies into, or along, a path of continuous forward travel for percussion initiation of same; means in combination with said conveying means at a forward point on said path of travel for sequential contact, while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same by force of resulting impact; and means for sequentially directing the thus-initiated charge assemblies away from said firing device during said period.
 2. In a firing device of claim 1, open means for guiding said charge assemblies along said path of continuous forward travel; means for conveying said charge assemblies sequentially to said open guiding means and then into said path of continuous forward travel; and said means for contact supported at a forward point on said guiding means.
 3. In a firing device of claim 2, said means for contact spaced from said conveying means a distance greater than the dimension of each said charge assembly contacted therewith, as measured on said path of travel, and forming a pivot for directing pivotal travel of the initiated charge assemblies from said device.
 4. In a device of claim 2, a conduit as said conveying means; and a tray member, as said open guiding means, at one end of said conduit.
 5. In a firing device of claim 4, said conduit and said tray member constituting an integral unit of construction formed by cutting a relief from one end of a tube.
 6. In a firing device of claim 4, at least a portion of a rimmed-wheel-type member, as said means for contact, supported in a plane substantially codirectional with said path of travel, and a rim portion thereof facing said conduit so as to contact a percussion-sensitive portion of each of the forwardly traveling charge assemblies.
 7. In a firing device of claim 4, a stationary contact member, as said means for contact, extending across at least a portion of said path of forward travel, and a surface portion thereof facing said conduit so as to contact a percussion-sensitive portion of each of the forwardly traveling charge assemblies, for said impact; and said stationary contact member disposed in an area across said path of forward travel equal to at leaSt about one-tenth the cross-sectional area of said conduit.
 8. In a firing device of claim 7, a fluid bypass extending, outside said conduit and tray members, from open communication with the interior of said conduit through a wall of said tray member intermediate said stationary contact member and said conduit.
 9. A firing device of claim 8, wherein said bypass extends through said wall at a point spaced from said stationary contact member a distance not more than about two-thirds of the dimension of each said charge assembly measured on said path of travel.
 10. In a firing device of claim 7, a ridged surface as said surface portion, and the ridge thereof facing said conduit for said contact.
 11. In a firing device of claim 4, said tray member containing a slot extending along its inner wall portion codirectionally with said path of forward travel; a bellcrank lever pivotally secured at its pivot point to said tray member; an arm of said bellcrank lever having a length at least as great as the dimension of said charge assembly measured on said path, and movable into and out of said slot about said pivot, and the other arm disposed across said path of forward travel so as to face said conduit when the first said arm is within said slot; a surface portion, of the last said arm member when disposed across said path, facing said conduit, so as to contact a percussion-sensitive portion of each said forwardly traveling charge assembly for said impact; and means for biasing the first said lever arm entirely within said slot.
 12. In a firing device of claim 11, a ridged surface, as said surface portion, and the ridge thereof facing said conduit for said contact.
 13. In a firing device of claim 1, a conduit for sequentially conveying said charge assemblies for said percussion initiation, and said conduit containing a slot formed by an opening, through a wall of an end section thereof, and extending substantially parallel to the longitudinal axis of said conduit through said conduit end; an elongated member, as said means for contact, secured at an intermediate point, to said conduit within the confines of said slot and pivotally movable, about said point, counterclockwise into said slot and clockwise from within said slot to a position extending through said slot into said conduit and across said path of forward travel; means for blocking clockwise travel of said elongated member farther than above described; means for biasing said elongated member in its position of farthest clockwise travel; and when said elongated member is blocked in said farthest position of travel, a surface portion of said elongated member facing the rearward end of said conduit so as to contact a percussion-sensitive portion of said charge assembly, while traveling in said path of forward travel, for said impact.
 14. In a firing device of claim 13, a ridged surface as said surface portion, and the ridge thereof facing said conduit for said contact.
 15. A firing device for initiating elongated delay-type percussion-initiatable explosive charge assemblies, and then delivering the initiated charge assemblies for detonation outside the firing system, comprising a conduit, and a tray member extending from one end thereof; said tray member being adapted to sequentially guide such charge assemblies along a path of continuous forward travel thereon for percussion initiation of same, and for pivotal travel of the thus-initiated charge as described hereinafter; said conduit being adapted to sequentially convey such charge assemblies to said tray and into said path of forward travel; impact means secured to said device and disposed in said path of forward travel for sequential contact with each said charge assembly to cause percussion initiation of same by force of resulting impact; said impact means being spaced as, and forming, a pivot for directing pivotal travel of said charge assembly from said tray member after said impact.
 16. A firing device of claim 15, wherein said pivot is spaced from saId conduit a distance of at least about 1.2 times the length of each said charge assembly contacted therewith.
 17. A firing device of claim 16, wherein said conduit and tray members constitute a unit of integral construction.
 18. In a firing device of claim 17, said conduit being tapered, along a portion of its length, from its rearwardmost end.
 19. A firing device of claim 17 for initiating an explosive cartridge assembly containing a primer element having an empty primed rifle cartridge case as a percussion-initiator means therefor; said rifle casing being disposed at one end of said charge assembly, and said impact member disposed in said path of forward travel so as to contact said empty primed rifle casing, when said charge assembly is conveyed, percussion end first, into said path of travel, to cause percussion initiation of same by force of resulting impact.
 20. A firing device of claim 19 wherein said impact member is at least a portion of a rimmed-wheel-type member positioned so as to directly face a rim portion thereof against said path of travel for contact of said rim portion with the empty primed rifle cartridge case element of each said charge assembly to cause said percussion initiation.
 21. A firing device of claim 20 wherein said empty primed rifle casing is rim fired.
 22. A firing device of claim 20 wherein said empty primed rifle casing is center fired.
 23. A firing device of claim 20 wherein said impact member is a complete wheel and is rotatably supported at its hub.
 24. A seismic exploration method, wherein complete delay-type percussion-initiatable seismic charge assemblies are initiated, emplaced, and fired in an underwater zone to provide energy for a seismic record, said method comprising sequentially conveying a plurality of said charge assemblies into, or along, a path of forward travel in said underwater zone; sequentially impacting said assemblies concurrently with said forward travel to percussion initiate same; and during the period of said delay, sequentially directing travel of the thus-initiated charge assemblies away from the zone of said percussion initiation into an adjacent area in said underwater zone for detonation.
 25. A seismic exploration method wherein complete delay-type percussion-initiatable seismic charge assemblies are initiated, emplaced, and fired in an underwater zone to provide energy for a seismic record, said method comprising sequentially delivering a plurality of said charge assemblies under force of fluid pressure into a charge-conveying means of a firing device in said underwater zone; said firing device comprising (1) means, as said charge-conveying means, for sequentially conveying said charge assemblies into, or along, a path of continuous forward travel for percussion initiation of same; (2) means in combination with said conveying means at a forward point on said path of travel for sequential contact, while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same by force of resulting impact; and (3) means for sequentially directing the thus-initiated charge assemblies from said firing device during the period of said delay; regulating said fluid pressure so as to impart sufficient force of impact for said percussion initiation with concomitant initiation of said charge assemblies and subsequent delay of priming action thereof, whereby during the period of said delay, travel of the thus-initiated charge assemblies is sequentially directed away from the zone of said percussion initiation into an adjacent area in said underwater zone for detonation.
 26. In a method of claim 25, sequentially delivering a plurality of said charge assemblies into a charge-conveying means of a firing device in said underwater zone; said firing device comprising (1) open means for sequentially guiding said charge assemblies along said path of continuous forward travel; (2) means, as said charge-conveying means, fOr conveying such charge assemblies sequentially to said guiding means and then into said path of continuous forward travel; and (3) means in combination with the guiding means supported at a point on said path of travel for contact with said charge assemblies to cause said percussion initiation, and the last said means being spaced from said charge-conveying means as, and forming, a pivot for directing sequential pivotal travel of the thus-initiated charges from the zone of said initiation into an adjacent area in said underwater zone; whereby the thus-initiated charge assemblies are sequentially and pivotally directed into said adjacent area for detonation.
 27. A system for generating seismic disturbances in a body of water which comprises a movable platform; means on said platform for storage of percussion-initiatable seismic explosive charge assemblies; a firing device, as a submersed firing station, comprising (1) means for sequentially conveying said charge assemblies into, or along, a path of continuous forward travel for percussion initiation of same; (2) means in combination with said conveying means at a forward point on said path of travel for sequential contact, while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same by force of resulting impact; and (3) means for sequentially directing the thus-initiated charge assemblies away from said firing device during the period of said delay; a delivery conduit connecting from said platform with said conveying means of said submersed firing station; fluid-pressure-generating means on said platform connecting with said delivery conduit for supplying force of fluid pressure for sequentially moving said charge assemblies from said platform through said delivery conduit to said conveying means, and into said impact.
 28. A system of claim 27 in which said firing device comprises (1) open means for sequentially guiding said charge assemblies along said path of continuous forward travel; (2) conduit means for conveying said charge assemblies sequentially to said guiding means and then into said path of continuous forward travel; and (3) means in combination with said guiding means at a forward point on said path of travel for sequential contact, while stationary, with said charge assemblies forwardly traveling along said path to cause percussion initiation of same by force of resulting impact, and for directing the thus-initiated charge assemblies from said guiding means; and said fluid-pressure-generating means connecting with said delivery conduit for sequentially moving said charge assemblies from said platform to said conveying means and then into and along said path of travel on said guiding means, for said impact.
 29. A system of claim 28 wherein, in said firing device, said means for contact is spaced as, and forms, a pivot for directing pivotal travel of the initiated charge assemblies from said device. 